primary has 12 distinct synonyms spread across 5 of its 8 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is secondary.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a preliminary election where delegates or nominees are chosen
one of the main flight feathers projecting along the outer edge of a bird's wing
(astronomy) a celestial body (especially a star) relative to other objects in orbit around it
coil forming the part of an electrical circuit such that changing current in it induces a current in a neighboring circuit
“current through the primary coil induces current in the secondary coil”
of first rank or importance or value; direct and immediate rather than secondary
“primary goals”
of or being the essential or basic part
“an elementary need for love and nurturing”
1 of the 8 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for primary.
Synonyms, antonyms and the broader and narrower relations for primary come from Princeton University’s WordNet. Full sources and licences.